Mosquitoes on the Decline

Below is the summary of mosquito activity in Iowa from the ISU Medical Entomology Laboratory. Mosquito surveillance in Iowa has been ongoing since 1969. During the summer months, the Iowa State University Medical Entomology Laboratory, in cooperation with the Iowa Department of Public Health and the University of Iowa Hygienic Lab, monitors mosquito populations and mosquito-borne diseases in Iowa.


The Iowa mosquito collection data for the year are available online at the Iowa Mosquito Surveillance website. The statewide average mosquito counts by week (including a comparison to last year's mosquito activity) are shown.


Summary for the week of July 8, 2013


Mosquito counts have been steadily declining all around Iowa. See the graph below.  We anticipate that this week's samples will follow the same trend and that next week's memo will be more of the same. However, notice that the current trap index is still higher than at any time last year.


Although the overall mosquito counts are decreasing, numbers of Culex species (including West Nile virus vectors) are not necessarily. For instance, Sioux City saw an increase in Culex numbers last week. These species can maintain a more consistent level of abundance throughout the year than the floodwater mosquitoes, which can show drastic ebbs and flows depending on rain.


Now is the time of year when we typically start collecting WNV-positive mosquitoes and chicken blood samples.  (The first case of West Nile virus was reported by the Iowa Department of Public Health on July 3, 2013.)  Please be vigilant with mosquito prevention and control practices!



Mosquito trap catch data from the ISU Medical Entomology Laboratory, July 14, 2013.Mosquito trap catch data from the ISU Medical Entomology Laboratory, July 14, 2013.


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